1. Field of the Invention:
This invention relates to a radial plunger type pump and more particularly to radial plunger type pump which has a counterweight for balancing the rotation of the eccentric cam shaft of the pump.
2. Description of the Related Art
A conventional radial plunger type pump is disclosed in FIG. 7. An eccentric cam shaft 33 is pivotally supported by pump housing 30 by bearing means 31 and 32 and plunger 35 is slidably provided in the cylinder 36 of the housing 30 to reciprocate within the cylinder 36 by the rotation of the cam shaft 33. For balancing the rotation, a pair of counterweight 37 are secured to the cam shaft 33 and disposed between the cam portion 34 and the bearings 31 and 32. The counterweights also serve as washers for preventing the axial movement of the cam shaft 33.
The counterweights are secured to the cam shaft by bolts and it may be difficult to change the weight of the counterweights for adjusting the rotation of the cam shaft 33 or may be damaged by the bolts during the repetitive use.